Conventionally, a so-called laminated evaporator has been widely employed as an evaporator for use in a car air conditioner. In the laminated evaporator, a plurality of flat, hollow members, each of which includes a pair of depressed plates facing each other and brazed to each other at their peripheral edge portions, are arranged in parallel, and corrugate fins are each disposed between and brazed to the adjacent flat, hollow members.
In recent years, evaporators have been required to be further reduced in size and weight and to exhibit higher performance. A known evaporator which fulfills these requirements includes a heat exchange core section configured such that heat exchange tube groups are arranged in two rows in an air flow direction, each heat exchange tube group consisting of a plurality of flat heat exchange tubes arranged at predetermined intervals; a first header which is disposed on a first-end side of the heat exchange tubes and to which the heat exchange tubes of one heat exchange tube group are connected; a second header which is disposed on the first-end side of the heat exchange tubes and rearward of the first header and to which the heat exchange tubes of the other heat exchange tube group are connected; a third header which is disposed on a second-end side of the heat exchange tubes and to which the heat exchange tubes connected to the first header are connected; and a fourth header which is disposed on the second-end side of the heat exchange tubes and to which the heat exchange tubes connected to the second header are connected. A refrigerant inlet is formed at a first end of the first header, and a refrigerant outlet is formed at an end of the second header that corresponds to the first end of the first header. A partition wall divides the interiors of the first and second headers at longitudinally intermediate portions. A refrigerant which flows into the first header from the refrigerant inlet passes through all the heat exchange tubes and all the headers and then flows out from the refrigerant outlet (refer to Japanese Patent Application Laid-Open (kokai) No. 2003-214794).
In contrast to the laminated evaporator, the evaporator described in the above-mentioned publication has implemented reduced size and weight and improved performance, so that the amount of condensed water generated on the surface of corrugate fins is increased. However, the evaporator described in the above-mentioned publication does not have a sufficient water drainage performance when the quantity of condensed water increases.
An object of the present invention is to overcome the above problem and to provide an evaporator which exhibits excellent drainage of condensed water.